\begin{table}[h]
  \caption{Muuntajan nimellisarvot ja ylajannitepuolelta mitatut arvot}
  \centering
  \begin{tabular}{r@{\hspace{2pt}}c@{\hspace{2pt}}lr@{\hspace{2pt}}c@{\hspace{2pt}}lr@{\hspace{2pt}}c@{\hspace{2pt}}l}
    \toprule
    \multicolumn{3}{l}{Nimellisarvot}&\multicolumn{3}{l}{Tyhjakayntikoe}&\multicolumn{3}{l}{Oikosulkukoe}\\ % & \multicolumn{40}{1}{something}
    \midrule
    $S_N$&$=$&$\SI{1000}{\kV\A}$&$U_0$&$=$&$U_{N1}$&$U_k$&$=$&$\SI{360}{\V}$\\
    $U_{N1}$&$=$&$\SI{6000}{V}$&$I_0$&$=$&$\SI{1.67}{\ampere}$&$I_k$&$=$&$I_{N1}$\\
    $U_{N2}$&$=$&$\SI{400}{\volt}$&$P_0$&$=$&$\SI{1550}{\watt}$&$P_k$&$=$&$\SI{8200}{\W}$\\
    $f_N$&$=$&$\SI{50}{\hertz}$&&\\
    \bottomrule
    \multicolumn{6}{l}{Nimellisarvot}&\multicolumn{3}{l}{Oikosulkukoe}\\ % & \multicolumn{40}{1}{something}
    \multicolumn{3}{l}{Nimellisarvot}&\multicolumn{3}{l}{Tyhjakayntikoe}&\multicolumn{3}{l}{Oikosulkukoe}\\ % & \multicolumn{40}{1}{something}
    \multicolumn{6}{l}{Nimellisarvot}&more&text&here\\ % & \multicolumn{40}{1}{something}
  \end{tabular}
\end{table}
